Green Party MP Julie Anne Genter said it appeared the drive for more advertising dollars was "dumbing down" news programming. "Is that the sacrifice you are making?"

TVNZ chief executive and editor-in-chief Kevin Kenrick said he did not think of it as a sacrifice. The days when people got most of their news in a six o'clock television fix were gone.

"Consumers are looking for short, sharp soundbites. They are looking for a punchy delivery."

After an hour of news at six o'clock, another half hour of conventional current affairs was now too much for most people, he said.

"Given that our move is entirely driven around consumers' behaviour, we think it absolutely in the right territory. We are completely committed to it for the long term."

Seven Sharp, which premiered on February 4, is hosted by Ali Mau, Greg Boyed and Jesse Mulligan. It targets an interactive audience, with heavy references to social media.

Ratings showed 497,000 people tuned in for its opening night, but the audience has since shrunk. Earlier this month, TV3's Campbell Live attracted more viewers in the 7pm slot than TV1 for the first time.

Kenrick said the audience for Wednesday night's Seven Sharp doubled that of Campbell Live.